JP5108634B2 - Key exchange method - Google Patents

Description

  The present invention relates to a key exchange method for holding a common encryption key between communication nodes before performing encrypted communication.

  Conventionally, as a technique for safely and easily setting device setting information between devices used by connecting to a home network, one described in Patent Document 1 below is known.

Patent Document 1 discloses a program for connecting a portable data medium to a first device and communicating device setting information such as a WEP key to the data device when performing communication using a wireless LAN. The host name of the first device and the electronic certificate attached to the first encryption key are stored in the data medium. Then, the data medium is connected to the second device of the communication partner of the first device, the network address of the first device is specified from the host name of the first device, and the data medium is connected via the communication network. The device setting information is automatically notified by encrypted communication performed using the first encryption key stored in.
JP 2007-134819 A

  As described above, communication settings can be performed between devices in the home network. However, when a server outside the home network communicates with a plurality of devices in the home network, it is difficult to make various settings by confirming that the devices in the home network exist in the same home network. Met.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and provides a key exchange method for excluding communication, etc., from an out-of-home device that is not in the same home to the home authentication server by the home authentication server. For the purpose.

  The present invention relates to a key exchange method in a network system including an external server, an authentication server and a terminal connected to a predetermined local network, and a temporary encryption key and a terminal identifier generated by the terminal are transmitted by the authentication server. A first step of acquiring without going through a local network; a second step of transmitting an authentication request together with a temporary encryption key and a terminal identifier by a predetermined secure communication to an external server by an authentication server; Based on the terminal identifier included in the authentication request transmitted from the authentication server and the correspondence table of the terminal identifier and encryption key stored in advance, an encryption key corresponding to the terminal identifier of the terminal is obtained, A verification request including the received temporary encryption key and terminal identifier is sent to the terminal by secure communication using the encryption key. A third step of transmitting, and the terminal decrypts the verification request transmitted from the external server using the encryption key stored in advance, and the temporary encryption key included in the verification request and the generated temporary encryption key And the fourth step of transmitting the verification result to the external server, and the external server referring to the verification result transmitted from the terminal and the temporary encryption key generated from the external server and the generated temporary encryption key And the fifth step of transmitting a session key for communication between the authentication server and the terminal to the authentication server by predetermined secure communication, and the communication transmitted from the external server to the authentication server. A sixth step of storing the session key and the terminal identifier of the terminal in association with each other, and a seventh step of acquiring the communication session key by the terminal.

  Specifically, according to the present invention, (1) in the first step, as an effect that does not go through the local network, it is possible to recognize the same house. (2) Then, in the third and fourth steps of claim 1, by transmitting the result of the collation from the external server to the terminal and returning the collation result to the external server, the terminal at the external server Can be confirmed to actually exist. For the first time, the external server creates a session key for communication between the authentication server and the terminal by the above authorizations (1) and (2), that is, authorization that the terminal is in the same house and that the terminal actually exists. Send it to have.

  As a result, access from outside devices can be eliminated, and when the center server requests the creation of a session key by impersonating an actual terminal, the verification result from the terminal is not returned to the external server. The effect of eliminating impersonation can be demonstrated.

  According to the present invention, it is possible to realize secure communication by recognizing that an external server is a terminal and an authentication server constituting a predetermined local network and setting an encryption key in the terminal.

  That is, the present invention assumes that secure communication between the authentication server and the external server and between the terminal and the external server has been established, and the session key between the authentication server and the terminal is mutually authenticated under the authorization of the same home. In this case, in the network such as a wireless LAN, communication from an external device not in the same house to the authentication server can be excluded by the authentication server.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The present invention is applied to a network system configured as shown in FIG. In this network system, a center authentication server 1 as an external server and a home authentication server 3 (AS) and a home device 2 (terminal) included in a local network are connected to the Internet NW, which is a general general-purpose line. Has been configured. Such a network system performs key exchange necessary for secure communication between the center authentication server 1 and the home device 2 by the center authentication server 1, the home authentication server 3, and the home device 2 operating with each other. Is. Thereby, in the network system, the center authentication server 1 recognizes that the home device 2 and the home authentication server 3 are devices in the same home, and sets the encryption key of the home device 2 in the home authentication server 3 It is.

  In this network system, the in-home device 2 and the in-home authentication server 3 communicate according to a communication protocol compliant with a predetermined local network. Specifically, this local network relays a radio signal transmitted and received between the home device 2 and the home authentication server 3 by the data transfer external device 4 according to a protocol for performing a predetermined wireless LAN. Thereby, the certainty of transmission / reception of a radio signal within the local network is ensured.

  In such a network system, the home authentication server 3 functions as a controller that controls and monitors the home device 2 in the local network. In this network system, the in-house authentication server 3 receives a request from a request terminal device such as a user's mobile phone (not shown) and provides a service to the user such that a response to the request is returned to the request terminal device. It is.

  In such a local network, a plurality of home devices 2 are installed in the home with respect to a single home authentication server 3. Examples of the in-home device 2 include an electric lock, a temperature sensor, a human sensor, an air conditioner, and lighting installed in a house. These home devices 2 are connected to a home authentication server 3 included in the local network. The home authentication server 3 performs processing for acquiring a variable value from the home device 2 and operating it. The home authentication server 3 communicates with a user terminal or application server (not shown), and notifies a variable value indicating the state of the home device 2 that is a home device in response to a request from the user terminal or application server.

  As a method of connecting the home devices 2 with each other and the home device 2 and the home authentication server 3 in the local network, and as a method of connecting the request terminal device or the center authentication server 1 with the home authentication server 3 and the home authentication server 3 over the Internet NW. For example, a device using an embedded network technology may be used, and a predetermined multiplex transmission system (Numast) that realizes transmission and reception of signals by performing baseband transmission in which the home device 2 and the home authentication server 3 modulate the pulse width. Communication) or a distributed control network technology called LON (Local Operating Network).

  As shown in FIG. 2, the home device 2 is provided with a MOS (Micro Object Server) function unit 21 for transmitting and receiving variable values including detection values and state values of the home device 2 between middlewares. Is implemented with an OAS (Object Access Server) function unit 31 that performs routing processing between middleware, recognition processing of the in-home device 2, and the like, and the request terminal device sends a control / monitoring request to the in-home device 2 to be controlled. An OAL (Object Access Library) function unit (not shown) that outputs and displays the status of the home device 2 is mounted.

  In the home device 2, an application processing unit 22 and an interface module 23 are connected to the MOS function unit 21.

  For example, when the application processing unit 22 functions as a sensor, an application code for acquiring a detection value is stored, and the detection value is held and transferred to the MOS function unit 21.

  The interface module 23 performs processing of a data link layer, a network layer, and a transport layer in an OSI (Open Systems Interconnection) reference model. For example, processing according to Ethernet (registered trademark) is performed in the data link layer, processing according to IP (Internet Protocol) is performed in the network layer, and processing according to UDP is performed in the transport layer. Capabilities such as a communication protocol version and a communication speed of the interface module 23 are stored in the capability table 24 and can be acquired by the OAS function unit 31.

  Further, as will be described later, the interface module 23 performs processing for the home device 2 to perform secure communication with the home authentication server 3, and for the home device 2 to perform secure communication with the center authentication server 1. Process. The procedure for performing this secure communication will be described later.

  The MOS function unit 21 functions as middleware between the application layer by the application processing unit 22 and the transport layer by the interface module 23. The MOS function unit 21 is given an object ID 21d by the OAS function unit 31 in order to identify that the in-home device 2 is an object in the device embedded network technology. The object ID 21 d is stored in a packet transmitted to the home authentication server 3 when communicating with the OAS function unit 31.

  The MOS function unit 21 performs an operation defined by a function 21a, an event 21b, and a variable 21c. The operation of the MOS function unit 21 is defined as a service table 21e and can be acquired as an interface ID (IID) by the OAS function unit 31 of the home authentication server 3.

  When the in-home device 2 is a sensor, the function 21a is a detection value output function, the event 21b is an event for outputting the detection value when the detection value becomes a predetermined value, for example, and the variable 21c is the detection value itself. . Such a home device 2 generates an event at event 21b when the detected value reaches a predetermined value, and outputs the detected value of variable 21c by function 21a.

  Such a home device 2 stores a temporary encryption key and an encryption key for the home device 2 to exchange encryption keys with the center authentication server 1. The temporary encryption key is data necessary to store the encryption key of the home device 2 in the home authentication server 3, and the encryption key is actually encrypted so that the home device 2 performs data communication with an external communication device. It is data necessary for performing. The temporary encryption key is stored in, for example, a portable storage medium sold together with the home device 2. In this case, the temporary encryption key is used by the home authentication server 3 when the portable storage medium is read by the playback device of the home authentication server 3 by the operator. Further, the temporary encryption key and the storage location of the encryption key may be stored together with the object ID 21 d or may be stored in the capability table 24. The temporary encryption key and the process using the encryption key will be described later.

  The OAS function unit 31 is connected to the server function unit 32 and the communication module 33.

  The server function unit 32 performs overall control of the OAS function unit 31 and the communication module 33. When the user wants to perform communication for controlling / monitoring a certain home device 2, the server function unit 32 is supplied with a request to that effect and sends a response to the request to the home device 2 via the communication module 33. Send back. The server function unit 32 exchanges information between the home device 2 and the center authentication server 1 when setting an encryption key in the home device 2. The operation of the home authentication server 3 at the time of this key exchange will be described later.

  The communication module 33 communicates with the interface module 23 of the home device 2 and also communicates with the center authentication server 1. The communication module 33 performs data link layer, network layer, and transport layer processing in the OSI reference model. For example, processing according to the wireless LAN is performed in the data link layer, processing according to IP is performed in the network layer, and processing according to TCP or UDP is performed in the transport layer. When each in-home device 2 includes various interface modules 23, the communication module 33 performs communication protocol version for each device having the in-home device 2 and other OAS function units 31 according to the control of the device access controller 31c. The communication processing according to the capability of the home device 2 such as the communication speed is performed.

  The communication module 33 performs a process of acquiring the encryption key of the in-home device 2 using the temporary encryption key of the in-home device 2 existing in the same house by the process described later. Then, this encryption key is stored in a storage unit (not shown), and a correspondence table between the home device 2 and the encryption key is created. Thereafter, when communication is performed with the in-home device 2 stored in the correspondence table, secure communication is performed according to a predetermined encryption algorithm using the encryption key.

  The OAS function unit 31 functions as middleware between the processing of the server function unit 32 and the transport layer processing by the communication module 33. The OAS function unit 31 includes a device access server 31a, service information 31b stored in a predetermined memory, and a device access controller 31c.

  The device access server 31a receives a request from the client via the communication module 33 and the server function unit 32 in order to communicate with the client (OAL). The device access server 31a controls the operation of transmitting the request to the home device 2 via the device access controller 31c and the communication module 33. As a result, the device access controller 31c transmits the request from the request terminal apparatus 1 to the home device 2 and controls the home device 2.

  The device access controller 31 c searches the service table 21 e and the capability table 24 of the home device 2 via the communication module 33 in order to acquire the interface definition and service information of the home device 2. Thereby, the device access controller 31c determines what service (function 21a, event 21b, variable 21c) each home device 2 has, and the correspondence relationship between the object ID 21d of each home device 2 and the service list Is created.

  Further, as will be described in detail later, the OAS function unit 31 provides the object identifier, the device name representing the service of the home device 2, the variable value held by the home device 2, and the variable as the service information 31b, as will be described later. A variable value table including a state acquisition time that is a value acquisition time is stored. Further, the OAS function unit 31 stores permissible time information for each device name as a threshold value indicating whether or not each variable value is old information.

  Further, the device access controller 31c receives the contents of the capability table 24 that the in-home device 2 has, and recognizes what capability (communication protocol version, communication speed) each in-home device 2 has. .

  When the event packet of the event is received by the MOS module 21 at the communication module 33, the device access controller 31c analyzes the event packet by the device access controller 31c and notifies the device access server 31a. When a request from the request terminal device 1 is transmitted to the in-home device 2, the MOS function unit 21 that can respond to the request is recognized with reference to the service information 31b. Then, the destination object ID 21 d is added to the request, and the packet is transmitted from the communication module 33 to the home device 2 in accordance with the capability of the home device 2.

  The OAS function unit 31 is given an object ID 31d (OID) so that other middleware-compatible devices can identify the OAS function unit 31. This object ID 31d is stored in a packet to be transmitted when communicating with the middleware-compatible device such as the MOS function unit 21 of the in-home device 2 or the request terminal device 1 (mobile phone or personal computer) in which another OAL is mounted. .

  Since the encryption key of the home device 2 is not set when the home authentication server 3 is installed, such a home authentication server 3 sets the encryption key of the home device 2 and communicates with the home device 2. It is necessary to perform secure communication. Therefore, the home authentication server 3 includes a mechanism for accurately acquiring the temporary encryption key of the home device 2 without the third party knowing the temporary encryption key. For example, when the temporary encryption key of the home device 2 is stored in a portable storage medium sold together with the home device 2, the home authentication server 3 uses the medium reading device (not shown) to store the temporary encryption key of the home device 2. To get. Thereby, the temporary encryption key of the home device 2 installed in the same home can be acquired without leakage of the temporary encryption key.

  The home authentication server 3 can acquire and store the encryption key of the home device 2 existing in the same home using the temporary encryption key. This processing will be described later.

  Next, an operation of setting the encryption key of the home device 2 existing in the same house by the center authentication server 1, the home device 2 and the home authentication server 3 will be described with reference to FIG.

  In this network system, it is assumed that an encryption key is set in the home device 2 and the home authentication server 3 at the time of manufacture. It should be noted that the encryption key may be set when the home device 2 and the home authentication server 3 are installed as long as it is before the actual operation. The encryption keys held by the home device 2 and the home authentication server 3 are stored in advance in the center authentication server 1 in association with the device identifiers (object IDs) of the home device 2 and the home authentication server 3. . Thereby, the home device 2 and the home authentication server 3 can perform secure communication with the center authentication server 1 at the time of installation. The encryption method between the center authentication server 1 and the home device 2 and home authentication server 3 is a common key encryption method. Hereinafter, in such a network system, the center authentication server 1 recognizes that the home device 2 and the home authentication server 3 are devices in the same home, and sets the encryption key of the home device 2 in the home authentication server 3 The operation to be performed will be described.

  First, in step ST1, the home device 2 generates a temporary encryption key. The temporary encryption key of the home device 2 is generated by a method using a random number generator (not shown) or a pseudo random number generated by software processing when the home device 2 itself generates the temporary encryption key.

  Then, the temporary encryption key S2 of the home device 2 together with the device identifier S1 of the home device 2 is acquired by the home authentication server 3 installed in the same home. Thereby, the temporary encryption key (temporary encryption key S2) and the terminal identifier (device identifier S1) generated by the terminal (home device 2) are acquired by the authentication server (home authentication server 3) without going through the local network. Is realized.

  As a method for the home authentication server 3 to acquire the temporary encryption key S2 of the home device 2, a method in which a predetermined eavesdropping is not performed is employed in order to prevent a third party from eavesdropping on the temporary encryption key. Specifically, a method for causing the in-home authentication server 3 to read a portable recording medium previously mounted on the in-home device 2 or an external device connection mechanism in each of the in-home device 2 and the in-home authentication server 3 to provide local serial only It may be transmitted via a communication path or may be transmitted via a dedicated external device.

  When the home authentication server 3 acquires the device identifier S1 and the temporary encryption key S2 from the home device 2, the authentication request S3 including the device identifier S1 and the temporary encryption key S2 is encrypted and transmitted to the center authentication server 1. At this time, the home authentication server 3 performs a partner authentication process with the center authentication server 1 or performs a process of transmitting an authentication request S3 using the encryption key of the home authentication server 3 itself. Secure communication with the. As a result, the authentication server (home authentication server 3) makes an authentication request to the external server (center authentication server 1) together with the temporary encryption key (temporary encryption key S2) and the terminal identifier (device identifier S1) by predetermined secure communication. The step of transmitting (authentication request S3) is realized.

  Next, when the center authentication server 1 receives the authentication request S3 from the home authentication server 3, the center authentication server 1 refers to the device identifier of the home authentication server 3 included in the authentication request S3 and uses the encryption key of the home authentication server 3 Decrypt.

  And the center authentication server 1 is based on the correspondence table of the device identifier S1 included in the authentication request S3 transmitted from the home authentication server 3 and the device identifier and encryption key of the home device 2 stored in advance. An encryption key corresponding to the terminal identifier of the in-home device 2 is acquired, and a verification request S4 including the received device identifier S1 and temporary encryption key S2 is transmitted to the in-home device 2 by secure communication using the encryption key. .

  Here, as a method for the center authentication server 1 to establish a connection with the home device 2, the network address (IP address) of the home device 2 is stored in the center authentication server 1 in advance, and the home device from the center authentication server 1 is stored. 2 is a request for establishing a communication connection.

  Next, the in-home device 2 collates the temporary encryption key S2 generated in step ST1 with the temporary encryption key S2 transmitted from the center authentication server 1 (step ST2), and whether the mutual temporary encryption keys match. A verification result S5 indicating whether or not is returned to the center authentication server 1.

  That is, the terminal (in-home device 2) decrypts the verification request S4 transmitted from the external server (center authentication server 1) using a pre-stored encryption key, and the temporary encryption included in the verification request S4. The key S2 is collated with the temporary encryption key S2 generated at step ST1.

  Then, the in-home device 2 transmits the verification result S5 to the external server (center authentication server 1). In addition, when transmitting collation result S5, it is not necessary to be secure communication or secure communication.

  At this time, when the in-home device 2 collates the temporary encryption key S2 included in the verification request S4 with the generated temporary encryption key S2, the expiration date of the generated temporary encryption key S2 is determined and the verification result is changed. You may do it. That is, a period from the time when the temporary encryption key S2 is generated by the home device 2 or the time when the home authentication server 3 acquires the temporary encryption key S2 to the time when the temporary authentication key S2 is received from the center authentication server 1 is predetermined. It is determined whether it is within the expiration date. Then, when the expiration date has expired when viewed from the reception time of the temporary encryption key S2 transmitted from the center authentication server 1, the matching result that the temporary encryption key S2 matches is not obtained.

  Next, the center authentication server 1 obtains the temporary encryption key S2 generated by the home device 2 and the temporary encryption key S2 transmitted from the center authentication server 1 to the home device 2 from the collation result transmitted from the home device 2. If they match, the communication session key S6 is transmitted to the home authentication server 3. The communication session key S6 is different from the temporary encryption key included in the authentication request S3 and the temporary encryption key included in the verification request S4, and is newly generated by the center authentication server 1 by generating a random number or the like. .

  On the other hand, if the temporary encryption key S2 generated by the home device 2 and the temporary encryption key S2 transmitted from the center authentication server 1 to the home device 2 do not match, the center authentication server 1 determines that the home device 2 The encryption key for use is not transmitted to the home authentication server 3.

  In this way, the center authentication server 1 transmits the temporary encryption key S2 of the home device 2 transmitted from the home authentication server 3 to the home device 2, and the temporary authentication key S2 generated by the home device 2 and the center authentication server 1 The temporary encryption key S2 transmitted from is collated.

  Then, when both temporary encryption keys S2 match from the home device 2 to the center authentication server 1, the verification result is directly transmitted from the home device 2 to the center authentication server 1. Thereby, the center authentication server 1 recognizes that the home authentication server 3 and the home device 2 are installed in the same home, and stores the encryption key for the home device 2 in the home authentication server 3. be able to.

  When the home authentication server 3 receives the encryption key for the home device 2 from the center authentication server 1 in step ST4, the home device 2 associates the received home device 2 with the device identifier of the home device 2. Stores the encryption key for use. Thereby, the home authentication server 3 can store the encryption key of the home device 2 that exists in the same home and can communicate with the center authentication server 1 in association with the device identifier of the home device 2.

  Then, the home authentication server 3 transmits the stored session key S7 for the home device 2 to the home device 2 for storage. At this time, the in-home authentication server 3 causes the in-home device 2 to acquire the encryption key by the same method as the method in which the temporary authentication key S2 generated in step ST1 is acquired by the in-home authentication server 3. That is, the communication session key S7 stored in the home device 2 is stored without going through the local network. The communication session key S7 may be transmitted after being encrypted with the temporary encryption key S2 generated in step ST1 via the local network.

  As described above, according to the network system to which the present invention is applied, it is recognized that the center authentication server 1 as an external server is the in-home device 2 and the in-home authentication server 3 constituting a predetermined local network. Secure communication can be realized by setting an encryption key in the device 2.

  Specifically, according to this network system, (1) as an effect that does not pass through the local network, it is possible to authenticate the same house. (2) The center authentication server 1 transmits the address to the address of the in-home device 2, and the in-home device 2 returns the collation result to the center authentication server 1. Can be confirmed to actually exist. For the first time, the center authentication server 1 performs a communication session between the home authentication server 3 and the home device 2 by the above-mentioned authorizations (1) and (2), that is, the authorization that the home device 2 actually exists. Create keys and send them to each other.

  As a result, it is possible to eliminate access from outside devices, and when the center authentication server 1 asks the center authentication server 1 to create a session key by impersonating the actual in-home device 2, the verification is performed from the terminal. Since no result is returned, the effect of eliminating impersonation can be exhibited.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

1 is a configuration diagram of a network system to which the present invention is applied. It is a block diagram which shows the functional structure of the household device in a network system to which this invention is applied, and a household authentication server. It is a sequence diagram which shows the exchange of the information exchanged among a center authentication server, a home device, and a home authentication server in the network system to which this invention is applied.

Explanation of symbols

1 Center Authentication Server 2 Home Device 3 Home Authentication Server 4 External Device for Data Transfer 21 MOS Function Unit 21a Function 21b Event 21c Variable 21d Object ID
21e service table 22 application processing unit 23 interface module 24 capability table 31 OAS function unit 31a device access server 31b service information 31c device access controller 31d object ID
32 Server Function Unit 33 Communication Module

Claims (3)

A key exchange method in a network system comprising an external server, an authentication server and a terminal connected to a predetermined local network,
A first step of acquiring a temporary encryption key and a terminal identifier generated by the terminal without going through the local network by the authentication server;
A second step in which the authentication server transmits an authentication request together with the temporary encryption key and the terminal identifier to the external server by predetermined secure communication;
Based on the terminal identifier included in the authentication request transmitted from the authentication server and the terminal identifier and encryption key correspondence table stored in advance, the external server performs encryption corresponding to the terminal identifier of the terminal. A third step of acquiring a key and transmitting a verification request including the received temporary encryption key and the terminal identifier to the terminal by secure communication using the encryption key;
The terminal decrypts the verification request transmitted from the external server using an encryption key stored in advance, and compares the temporary encryption key included in the verification request with the generated temporary encryption key. A fourth step of sending the collation result to the external server;
When the external server refers to the verification result transmitted from the terminal and the temporary encryption key transmitted from the external server matches the generated temporary encryption key, the predetermined secure communication A fifth step of transmitting a session key for communication between the authentication server and the terminal to the authentication server;
A sixth step in which the authentication server stores the communication session key transmitted from the external server in association with the terminal identifier of the terminal;
And a seventh step of acquiring the communication session key by the terminal.   The first step of obtaining a temporary encryption key by the authentication server includes a step of reading by the authentication server a storage medium storing the temporary encryption key provided in the terminal. Key exchange method.   In the fourth step of verifying the temporary encryption key included in the verification request and the generated temporary encryption key, the terminal determines the expiration date of the generated temporary encryption key and generates the verification request when the verification request is received. 3. The key exchange method according to claim 1, wherein when the temporary encryption key has expired, the verification result does not match the temporary encryption key.

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